New boiler - 22mm gas supply

[empty_vessel]

I've just had the heating engineer round to look at my dodgy Alpha 240P boiler - I think it's on its last legs...he suggested replacing it for a Worcester-Bosch Greenstar 37CDi. Old boiler was obviously really inadequate in terms of of output but he did notice one sticking problem to installing a new one - the gas supply pipe.

Now from the meter the gas supply runs alongside the house then disappears into a wall all good up to here because it's 22mm copper pipe (it's not sleeved going through the wall but I can live with that). Problem is the gas supply pipe enters my kitchen at 15mm and there's some monkey work gone on just below the boiler to transfer to the inlet size of the boiler (22mm). Total length overall is approx 10m, anywhere between 5m and 7m is 22mm with the remainder being 15mm. There are about nine 90 degree elbows in the supply pipe to the boiler and there is a 15mm branch to my 4 burner gas hob.

I don't think I can get away with the supply pipe as it currently stands, how much do you think it would cost to have someone lift the carpet in the bedroom, find the supply pipe in the floor void and fit 22mm for the remainder of the run to the boiler? Obviously a lot of factors but rough guide for that sort of work? If anyone knows of any tables where I could work out what diameter pipe is needed (if greater than 22mm) that would be great.

I'm in Dorchester so if anyone can recommend any quality fitters I'd appreciate it. I really wish they wouldn't let people who are willing to do this sort of cowboy work anywhere near houses!

 

[Gasguru]

With that lenght of run, that many bends and the hob feed as a minimum it will need to be 28mm the full lenght.

Whats wrong with the Alpha? Loads of these still running well. For the cost of the new 28mm gas run you could probably sort out the existing boiler.

 

[empty_vessel]

Intermittent DHW and CH, I think we're going to be in the house for at least 4 years so don't want to chuck good money after bad to get this thing sorted.

I think the APS is the problem with the Alpha at the moment so going to try that before doing the new boiler option (with associated supply pipe saga). If it's not that then probably the PCB or DHW temp sensor but the sound coming from the boiler just before it cuts out sounds like a loose connection somewhere, possibly inside the APS, not sure but will try that anyway.

I need a qucik fix - I've got the in laws coming for Christmas and can't be doing with her mum complaining about it being cold!

 

[Gasguru]

I've never changed an APS or pcb in the 240 yet. The symptoms in your other posting could be a very easy and cheap fix. Since it involves the combustion chamber and several spire clips will break I 'm not going any further than suggesting you call in an Alpha engineer...have you contacted Alpha for contacts in your area?

Only cowboys and amateurs throw parts at boilers.

 

[empty_vessel]

Nope, got a heating engineer recommended to me. The Alpha helpline said DHW temp sensor or PCB - sounds like they're trying to sell parts! The boiler was used for house before it was extended - 1 bedroom and ensuite added plus new lounge, boiler was then re-sited.

I'll try and speak to Alpha for contacts before committing to anything - thanks!

 

[empty_vessel]

Just an update - got fed up waiting for the recommended Heating Engineer so I called Alpha. They gave me the name of the local contractors, they came round 3 days later, serviced the boiler and now it sort of works.

Engineer said that it probably needs a new diverter valve and dhw heat exchanger. DHW is a bit cool at the mo and radiators do heat up nice and quick when having a shower but he quotes about £450 - if the boiler will rapidly break down again if I leave it then I'll get it done.

To get to the point, is it worth getting these components changed now or should I wait? If I don't get it changed I'm going to give the system a good clean with Fernox F3 then inhibit with F1 and it's not had any inhibitor in it as far as I can work out. Could the cleaner fix the problem or is it not worth chucking almost £45 worth of cleaner and inhibitor down the drain?

Thanks for any help in advance.

 

[Gasguru]

Either refurb the diverter (parts no more than £60...diverter recon kit, diapgragm kit, auto air vent) or replace the diverter (I think the Baxi parts will fit and are considerably cheaper than Alpha). The plate exchanger if it's clogged can easily be cleaned and replacement is highly unlikely.

Make sure the expansion vessel is checked, the venturi/fan checked/cleaned and it's worth checking the heating return filter is clean.

Total cost should be less than half you're being quoted.

A cleaning chemical is unlikley to have much effect on the diverter if it's partially siezed. Refill with inhibitor.

 

[empty_vessel]

Thanks - sounds like something I can get on with. Can you suggest anywhere reasonable to get hold of the diverter recon kit (or a baxi diverter as you suggest)?

I suppose the plate exchanger is just a case of remove and clean with industrial descaler?

I'll check the heating return filter as soon as I get the chance.

Many Thanks!

 

[cozzmic]

Going back to the poster he has said that the gas pipe might need upgrading for the new boiler if it goes in. I think the warm hot water might be down to the existing gas supply being undersized therefore not giving the heat require for that side of the boiler, eg CH gas pressure requirements are lower than HW supply gas pressure.

Just a thought.

 

[empty_vessel]

Sorry should have added that the Hot Water has been fine in the past (although this is the first winter we've lived in the house), which leads me to think that it is a component failure issue that seems to be getting a bit worse.

 

[ChrisR]

GG's spot on I reckon. Clean the hex first - a lot easier than dismantling the diverter! Then see if the CH pipes get hot when you're running HW.
The temp sensors do "go " on these, and get scaled up etc. (cleanable)

These boilers run OK on appalling gas supplies - just as well because that's what most of them seem to get!

 

[empty_vessel]

I've found a website selling the kits mentioned above and I'm going to order them, just a quick sanity check though, to recon the diverter vlv, clean the heat exchanger and recon the DHW flow vlv (while I've got it off anyway) will the following kits do?

Seal Kit 760 Repair 3 Port Vlv (Pt No 6.1000760)
Seal Kit 765 DHW Flow Vlv (Pt No 6.1000765)
Auto Air Vent (Pt No 1.010771)
Seal Kit 775 AAV/EXP VES/NTC/ (Pt No 6.1000775)

All from http://www.hccfspares.com/Part_Type3.aspx?Manufacture_ID=41&Part_Type=WASHER+KIT

I'm going to get some descaler to clean up the DHW Heat Exchanger (leave it in a bucket overnight) and pop the CH Rtn Filter out while I have the system drained and give that a clean too. Venturi and expansion vessel have already been checked by Alpha Heating Engineer when he serviced it so they're ok.

Any tips before I start draining boilers and taking things apart?

 

[empty_vessel]

Not the most successful weekend so far - I whipped the DHW heat ex out on Saturday, not that bad at all (I gave it a quick rinse through and got rid of the scale and sludge using domestic descaler) then I fitted a new towel radiator and flushed the system through a couple of times, water was pretty clean but gave all the rads a quick smacking with a rubber mallet to try and dislodge the sludge, if any, from the system.

Most annoying thing was following the manufacturers instructions to dose the system with Fernox F3 super concentrate. I know there are different ways of doing this but I though I'd do what the instructions said:

System was full and up to 1 bar pressure iaw the boiler instructions.
Shut off radiator I had chosen at lockshield and TRV (TRV was closed using plastic cap)
Vented said radiator at standard vent plug.
Attached Fernox dosing plastic thing and attached to mastic gun etc
Took up slack on mastic gun so plunger was against rear seal in tube but not pressurising tube.
Opened TRV v slowly as per Fernox instructions

Result - blown rear seal in mastic tube, Fernox F3 all over me and in a bucket I had with me £23 down the drain.

Now next time I'll be dosing into an completely empty radiator then removing dosing gear from vent plug and sealing up etc before opening up rad valves.

Anyone think I've got a leg to stand on asking Fernox for a replacement tube because their instructions are so rubbish?

 

[DP]

Empty vessel, a little bit of understanding is called for as well besides what the instructions say. The idea is to make space within the radiator for the descaler. This is why you drop the water level in the radiator. Once the chemical is introduced into the radiator, that too is going to raise the pressure in the radiator (and blow back). In order to equalise, one has to negate the pressure created by pumping in the chemical by removing the excess pressure. Now and only now can you remove the tube and whatsit with no fear of loosing the expensive chemicals. The plugs on the rad are secured and water allowed to enter the rad.

Purge air and let chemicals do the job. All common sense.